Study of Pion Photoproductions on Fewbody Systems

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One of the main Purposes of this project is to apply a dynamical model of the pion photoproduction on the nucleon constructed by us to fewbody systems such as deuteron and ^3He nucleus. By doing this we hope that one can get a deeper understanding on the pion photoproduction mechanism for the fewbody systems through the dynamical modl.We have investigated "the pion electroproduction reaction ^3He (e, e'pi) " to study the preformed DELTA-component in the ^3He wave function.(1) We have shown that the previous analysis based upon the isospin symmetry with the DELTA-dominance is not valid. It is argued that there is a considerable contribution from the Born diagrams. This implies that the large enhancement of the DELTA knock-out process in the pi^+/pi^- ratio measurement should not be expected.(2) We have calculated the coincidence cross sections of ^3He (e, e'pi) in the DELTA-resonance energy region. With the cross sections, we have explored the sensitivity to the DELTA-component in ^3He wave function. It has been shown that the probability effect of the DELTA-component is negligible in the transverse cross sections and is very small even in the longitudinal cross sections. It has been also suggested that the interference effect of the DELTA-component is required to obtain the sizable sensitivity.